From: Joe Chang (changjoe@earthlink.net)
Date: Sun May 23 2004 - 14:24:34 GMT-3
I think it's a general question, applicable to any traffic shaping scenario
in which the traffic rate exceeds the CIR for a significant length of time.
----- Original Message -----
From: "Kenneth Wygand" <KWygand@customonline.com>
To: "Joe Chang" <changjoe@earthlink.net>; <ccielab@groupstudy.com>
Sent: Sunday, May 23, 2004 12:46 PM
Subject: RE: Traffic Shaping question
> Joe,
>
> Can you provide a basic configuration example illustrating your
> question?
>
> Kenneth E. Wygand
> Systems Engineer, Project Services
> CISSP #37102, CCNP, CCDP, ACSP, Cisco IPT Design Specialist, MCP, CNA,
> Network+, A+
> Custom Computer Specialists, Inc.
> "The only unattainable goal is the one not attempted."
> -Anonymous
>
> -----Original Message-----
> From: Joe Chang [mailto:changjoe@earthlink.net]
> Sent: Sunday, May 23, 2004 12:34 PM
> To: Kenneth Wygand; ccielab@groupstudy.com
> Subject: Re: Traffic Shaping question
>
> You are absolutely correct, policing either marks or drops
> non-conforming
> traffic. I guess the idea behind traffic shaping is either 1) to make
> sure
> the upstream network never has to contend with "too much" traffic or 2)
> give
> the network all traffic but let it know which packets it can preferrably
> drop.
>
> However my question concerns traffic shaping - which does not mark (set
> the
> IP precedence) of overrun traffic. It's my fault - I didn't make that
> clear
> in the body of my question.
>
> ----- Original Message -----
> From: "Kenneth Wygand" <KWygand@customonline.com>
> To: "Joe Chang" <changjoe@earthlink.net>; <ccielab@groupstudy.com>
> Sent: Sunday, May 23, 2004 1:55 AM
> Subject: RE: Traffic Shaping question
>
>
> > Joe,
> >
> > There are two strategies you can employ, and your statements mesh two
> of
> them together in a way that it doesn't make logical sense, so in that
> way,
> you are correct!
> >
> > When you use the token bucket (policing in this case) algorithm, each
> packet passing through the algorithm is considered to "conform",
> "exceed" or
> "violate" the restrictions (depending on which form of policing you are
> using - "rate-limit" uses only the "conform" and "exceed" actions while
> "class-based policing" uses all three of the restrictions.)
> >
> > For arguments sake, lets say you are using the "rate-limit" command so
> all
> traffic can either "conform" or "exceed" the traffic contract you
> configure.
> For the traffic that exceeds, there are two strategies you can employ;
> you
> can send the traffic at a lower priority or you can drop the traffic
> completely. The first method, sending traffic at a lower priority,
> _will_
> allow you to exceed the CIR, but will ensure that all traffic that does
> exceed the CIR has its priority marked down. This way, if congestion
> occurs
> at a later router, that router will know which traffic has already
> exceeded
> a particular traffic contract and can selectively drop that traffic
> first.
> >
> > The other option, simply dropping the traffic completely, will always
> conform to the CIR, but will never send unconforming traffic.
> >
> > Hope this helps!
> > Ken
> >
> > -----Original Message-----
> > From: nobody@groupstudy.com on behalf of Joe Chang
> > Sent: Sat 5/22/2004 7:35 PM
> > To: ccielab@groupstudy.com
> > Cc:
> > Subject: Traffic Shaping question
> >
> >
> >
> > QoS is a real popular topic here!
> >
> > Does anyone know what happens to packets that are queued as a result
> of
> being
> > rejected by the token bucket algorithm? At what point are these
> packets
> > forwarded onto the transmit ring? Two streams result from the token
> bucket
> > function - one that conforms and one that doesn't. How and when can
> the
> > unconforming stream be sent without defeating the objective of traffic
> shaping
> > - keeping the average rate under the CIR?
> >
> > TIA
> >
> >
> _______________________________________________________________________
> > Please help support GroupStudy by purchasing your study materials
> from:
> > http://shop.groupstudy.com
> >
> > Subscription information may be found at:
> > http://www.groupstudy.com/list/CCIELab.html
> >
> >
> _______________________________________________________________________
> > Please help support GroupStudy by purchasing your study materials
> from:
> > http://shop.groupstudy.com
> >
> > Subscription information may be found at:
> > http://www.groupstudy.com/list/CCIELab.html
>
> _______________________________________________________________________
> Please help support GroupStudy by purchasing your study materials from:
> http://shop.groupstudy.com
>
> Subscription information may be found at:
> http://www.groupstudy.com/list/CCIELab.html
This archive was generated by hypermail 2.1.4 : Wed Jun 02 2004 - 11:12:15 GMT-3